1. Field of the Invention
The present invention relates to a sheet feeder for supplying a sheet(s) of paper to an image forming section of an image forming apparatus, and the image forming apparatus using the sheet feeder, and more particularly to a sheet feeder having a sheet stacking tray provided to be opened and closed with respect to a main body and being mainly suitable for manual sheet feeding, and an image forming apparatus using the sheet feeder.
2. Description of Related Art
Conventionally, an image forming apparatus is provided with a manual sheet feeder formed of an outer panel a part of which will be opened to allow manual loading of a sheet(s) therein in addition to a sheet cassette for supplying a sheet(s) therefrom. One example of such sheet feeders is disclosed in Japanese patent application publication No. 2005-298112. The sheet feeder in this publication is provided with guide members placed in contact with side edges of a stack of sheets to regulate the stacked sheets. Each guide member includes a posture maintaining means at one end to maintain the posture of the guide member. Each guide member further includes a pressing means at the other end to press the side edges of the stacked sheets. These guide members are used to prevent skewing (oblique shift) of a sheet to be conveyed.
However, the conventional sheet feeder mentioned above has the following disadvantages. In response to recent demands for downsizing of apparatus, it is becoming difficult to prevent the occurrence of sheet skewing. In association with downsizing of the image forming apparatus, a sheet tray such as a manual sheet feeding tray to be used by opening and closing a part of the apparatus also has been reduced in size of a lifting plate and other surrounding parts or components. Accordingly, sheet guides additionally provided in the lifting plate also have been reduced in size. This is a disadvantageous condition to prevent sheet skewing. Size reduction of the sheet guides will cause difficulty in adjusting the sheet guides to fit close to the sheet width. This is because such small sheet guides are unnoticeable and also difficult to grasp.
The present invention has been made to solve the foregoing problems of the conventional techniques. Specifically, the present invention has objects of providing a sheet feeder capable of properly conveying a sheet loaded on a tray with even an apparatus configuration adapted for downsizing, and providing an image forming apparatus using the sheet feeder.